*{margin: 0;padding: 0;}
a{text-decoration: none;
color:black ;}
header i{
    float: left;
    width: 22px;
    height: 18px;
    vertical-align: middle;
    position: absolute;
    right: 52px;
    top: 16px;
    background: url(../images/sprite.png) no-repeat 0px 0px;
}
header{
    width: 100%;
    height: 90px;
    background-color: #fff;
    line-height: 50px;
    z-index: 1;
}
header div{
    width: 1200px;
    height: 90px;
    margin: 0 auto;
    position: relative;
    display: flex;
    justify-content: center;
}
header img{
    width: 200px;
    height: 23px;
    position: absolute;
    top:30px;
    left: 50px; 
    float: left;
    cursor: pointer;
}
li:hover span{color: red;}
header .tu,.tul{
    list-style: none;
    cursor: pointer;
}
header .tu li{
    width: 100px;
    height: 30px;
    display: inline-block;
    font-size: 18px;
    position: relative;
    top: 20px;
}
.tu li:hover .tul{
     display: block;
} 
.tul{
    width: 100px;
    height: 160px;
    float: left;
    background-color: #fff;
    display: none;
}
.tul li{
    width: 100px;
    /* height: 50px; */
    margin-left: 10px;
}
  form{
    width: 200px;
    height: 40px;
    border-radius: 20px;
    background-color: #ccc;
    margin:10px;
    overflow: hidden;
    position: absolute;
    left: 900px;
    top: 13px;
    border:1px solid #ccc;
    transition: all 0.6s;
}
input{
    border:none;
    outline:none;
}
.text{
    width: 100%;
    height: 45px;
    padding-left:10px;
    color: #ccc;
    position: absolute;
    top: 1px; 
    text-align: left;
}
.mybutton{
    width: 80px;
    height: 38px;
    background-color: #f00;
    color:#fff;
    position:absolute;
    right:2px;
    top:1px;
    border-radius: 19px;
}
/*当表单元素处于聚焦时，表单元素form能够匹配上*/
form:focus-within{
    width: 270px;
}
.d1,.d2,.d3,.d4{
   text-decoration: none;
   text-align: center;
   color: black;
}
.d1{
   position: relative;
   top: 20px;
   left: 400px;
}
.d2{
    position: relative;
    top: 20px;
    left: 410px;
}
.d3{
    position: relative;
    top: 20px;
    left: 440px;
}
.d4{
    position: absolute;
    top: 20px;
    left: 820px;
    font-size: 18px;
}
section .p{
    width: 100%;
    height: 100%;
    background-color: #ccc;
}
.d4:hover{color: red;}